For some time, actuators have been known for delivering metered doses of medicament from aerosol canisters. Conventionally, these actuators comprise a tubular member for receiving a canister containing medicament; a mouthpiece for guiding medicament to the mouth of a user. In order to prevent dust etc. from entering the mouth piece when the actuator is not used, the actuator further may comprise a removable protection cap for the mouthpiece. The actuator, except for the protection cap, can be comprised of a single integral moulding in plastic material, or an assembly of two or more parts. It is of great importance that the protection cap is reliably attached to the mouth piece, to prevent dust or foreign particles etc. being collected within the inhaler and contaminating the inhaler at worst being inhaled or blocking the delivery channel. Therefore it is important to maintain cleanliness of the inhaler. However, it is of equal importance that the protection cap is simple to remove, so that any patient, for example, a physically impaired patient, is able to remove it and use the inhaler without hindrance.